Quick Smoke Domain is Solid Black
A general answer to this is because there are either no lights in your scene or you haven't computed the smoke simulation yet. To add a lamp to your scene, use ShiftA > Lamp and choose one. To simulate the smoke, you can just hit AltA or bake it to disk under Smoke Cache in the Physics panel (you must save the file first).

Also, the default Point lamp is a bit weak and might not illuminate the smoke properly depending on the angle viewed. A Hemi or Sun lamp should be sufficient for most tests.

Without any light



With a hemi lamp